The present invention relates generally to heat exchangers, such as those usable in forced air furnaces, and more particularly to an improved edge seal mechanism for heat exchangers of clamshell construction.
In the prior art, heat cxchangers of the clamshell type have been developed and utilized, based upon several advantages including their greater economy in fabrication, efficiency in use, etc. Such clamshell heat cxchangers arc formed from a matched pair of sheet metal workpieces, into which indentations are formed, to define upon joining thereof a passageway between such opposed clamshell elements for the hot products of combustion, which arc circulated therethrough for radiation therefrom.
In the prior art, clamshell heat exchangers have been joined at the edges by a variety of different mechanisms. For example, in each of U.S. Pat. No. 3,294,082 to Norris, U.S. Pat. No. 1,9207,174 to Jones, U.S. Pat. No. 3,324,845 to White, and U.S. Pat. No. 3,807,382 to Kennedy, various forms of planar flange elements are taught. Such planar flange elements may be joined in a variety of ways, including the disposition of a channel clement over the terminal portion of the planar flange elements for maintenance thereof in operative and sealing disposition, such as for example set forth in U.S. Pat. No. 1,927,174 to Jones. Of course, these planar flange elements and other edge joining elements have also been welded together to form edges which are scaled to maintain the hot combustion products therein.
Various improvements in sealing elements incorporating planar and other flange portions have been developed. One form of edge sealing structure of the prior art is set forth in U.S. Pat. No. 4,739,746 to Tomlinson. In that structure, a pair of individual plates are proformed to define opposed recesses, and the edges of the respective clamshell plates are secured together in scaled relationship by a terminal end portion of the plate having one plate flange portion wrapped and bent around the other plate flange portion, and then having both plate flange portions crimped across the longitudinal extent thereof by means of a cylindrical-shaped depression imposed longitudinally upon both of the respective plate flange portions.
Another edge sealing mechanism comprising crimped edges of the respective top and bottom heat exchanger clamshell plates is shown in U.S. Pat. No. 4,986,785 to Tomlinson. In this form of crimped edges, the edge of a top plate extends outwardly and bends downwardly to project from the crimped edge. Another bend is made near the end of the top plate. The corresponding edge of the bottom plate is then wrapped around the edge of the top plate. A gap exists between the plates and where the bottom plate wraps around the terminal portion of the edge of the top plate. Such gap allows the metal of the top plate to expand without adversely affecting the coupling, so that the top plate does not press against the bottom plate. After this wrapping of the bottom plate over the top plate, a perforation crimping is applied in and to the top surface of the wrapped-around portion, or fold, of the bottom plate. The gap and the perforated crimping edge features together form a plurality of gussets which are necessary to maintain a seal between the two plates. The gussets are set forth in evenly spaced array, and function to stretch the plate material to make the juncture tight from one end to the other, in order to assist in maintaining the seal. In this prior art gussetted structure, the bend near the end of the top plate is bent in a direction away from the terminal portion of the edge of the bottom plate.
In these and other prior art edge sealing mechanisms, various defects, disadvantages and deficiencies have been noted. In particular, the use of a bend of the edge portions of the top and bottom plates in a direction away from the terminal portion of the edge of the top plate (i.e., away from the joint) has caused opening up of the joint. Moreover, the use of such a bend away from the joint has necessitated the use of additional supplemental perforations or crimped edges (such as gussets) in order to attempt to maintain the seal. Consequently, the necessity for use of additional gussetting has resulted in the further necessity of processing by means of additional equipment, and that further processing enhances the possibility of error in the formation of these clamshell heat exchangers. Yet additionally, the necessity for the use of such gussetted edge structures has resulted in additional expense in the working and formation of such clamshell heat exchanger mechanisms.
In light of the above defects, disadvantages and deficiencies of the prior art, it is a material object of the improved sealing mechanism for a clamshell heat exchanger of the present invention to provide improved functioning, and to do so by means of a simplified and more stable structural mechanism.
It is also a material object of the improved edge seal mechanism for a clamshell heat exchanger of the present invention to provide a stable edge seal structure which will materially alleviate the tendency for the joint to open up as found in prior art edge seal structures.
These and other objects of the improved edge seal structure for a clamshell heat exchanger of the present invention will be better understood by those skilled in the art upon review of the following summary of the invention, brief description of the drawing, detailed description of preferred embodiments, appended claims and accompanying drawing.